ZWO FF90 APO - Flat-Field Apochromatic Refractor

Lightweight & Compact - Designed for Both Visual Observation and Astrophotography *Focus can be achieved within a back focus range of 45-75 mm, measured from the M54-M48 interface shoulder. Main Features Flexible Connectivity for Multiple Configurations Uniqueness Lightweight & Compact The ZWO FF90 APO features a 90 mm aperture and 609 mm focal length (f/6.8), offering an excellent balance between portability and performance. The optical tube weighs just 3.92 kg, with a total system weight of 4.52 kg including mounting rings and dovetail plate. Four-Element Optical Design The FF90 APO features a four-element, fully air-spaced apochromatic optical design. All four elements work together to deliver a flat imaging field without the need for an additional field flattener. One ED (extra-low dispersion) glass element is incorporated to effectively reduce chromatic aberration, resulting in improved color correction and image clarity. 44 mm Image Circle - Full-Frame Support With a 44 mm image circle, the FF90 APO fully supports full-frame sensors and a wide range of imaging setups. It delivers sharp star fields with excellent edge-to-edge performance, ensuring consistent image quality across the entire frame. Native Flat-Field Design The FF90 APO features a native flat-field optical design, eliminating the need for an additional field flattener. No complex back focus calculations or spacing adjustments are required -- simply attach your imaging setup and start capturing once focus is achieved. Convenient Design Course & Fine Focus Adjustment Equipped with a rigid 3-inch rack-and-pinion focuser, the FF90 APO offers precise control with a 1:10 course & fine focus adjustment mechanism. A built-in 360° rotator at the rear allows for smooth and accurate camera angle adjustments. Retractable Dew Shield The FF90 APO features a retractable dew shield, reducing overall length for improved portability. Precision CNC machining and a high-quality painted finish, combined with an internal anti-reflection coating, help minimize stray light and enhance image contrast. Quick-Release Mounting Rings The mounting rings are detachable, allowing for quick and easy setup or teardown of the telescope. Photography Extension Tube The FF90 APO includes a photography extension tube with a 2-inch filter thread, along with rear adapters in M48x0.75 and M54x0.75 standards. This allows for easy integration with a wide range of imaging accessories. Performance Optical Layout Star Field Map Product Diagram Specifications What's in the box? FF Series Telescope Comparison